A conventional relatively moving magnetic fluid seal device seals a gap between two members by bringing a magnetic fluid that is retained at one of the two members into contact with a surface of the other member.
An example configuration of a conventional magnetic fluid seal device is illustrated in FIG. 24. This is a configuration in which a magnet 103, which is commonly magnetized in an axial direction, is sandwiched between and adhered to two pole pieces 104, disposed in a nonmagnetic housing 101, and a magnetic fluid 105 is filled into gaps between the pole pieces 104 and a magnetic material shaft 102.
However, the following problems arise in the case of the above-described conventional technology.
Because the magnetic fluid seal device of the conventional technology is fixed to the housing, the tolerance of eccentricity between the housing and the shaft becomes equal to or less than the gaps between the pole pieces and the shaft, and high precision in the coaxiality between the housing and the shaft has been necessary.
In this configuration, there has also been the complication that the filling of the magnetic fluid must be conducted after assembly of the device, and there has been the drawback that it is difficult to manage the magnetic fluid filling amount.
Moreover, because a regular thickness is necessary for the magnet and the pole pieces, there has been a limit to thinning. There has also been the drawback that the magnet and the pole pieces must be adhered.
The present invention was devised in order to solved the problems in the above-described conventional technology, and it is an object thereof to provide an easily manufacturable magnetic fluid seal device that improves sealability by enlarging the tolerance of eccentricity of the two members, that can reduce variations in quality by making it possible to inject the magnetic fluid before device assembly, and that improves thinning by reducing structural members.